1. Technical Field
The present invention relates to the improvement of a device to hold an anastomotic site of coronary artery motionless and bloodless for the bypass operation, more in details, it relates to said device wherein the coronary artery bypass operation can be securely performed on the beating heart with an anastomotic site of the artery motionlessly and bloodlessly held in a safe and stable fashion.
The coronary artery (C) is a blood vessel to supply blood containing oxygen and nutrition to the myocardium of the heart (H) in order to keep the heart in good shape and consists of a right coronary artery (16)and a left coronary artery (7) both originating from the foot of sinus aortae (8). If there happens malfunction in the coronary artery (9) such as stenosis, occlusion and contracture, etc., the blood circulation of the artery is interrupted so that the discrepancy arises between the quantity of oxygen and nutrition actually supplied to the myocardium and that normally required therefore, with the result that ischemic heart diseases such as primary (cardiac arrest, angina pectoris, myocardial infarction, heart failure and arrythmia are invited and those who suffer from those diseases go in peril of their lives.
2. Prior Art
In light of the foregoing, it has been recently recognized that coronary artery bypass surgery is effective to cure those who suffer from such ischemic heart diseases as mentioned above. As a result of it, this surgery has become popular among the cardiovascular surgery practitioners.
In this connection, there are such well-known methods of the coronary artery surgery as a so-called "venous bypass grafting" whereby a circumventive blood vessel is formed by bypassing a venous blood vessel excised from the lower limb between the proximal side of the artery (in the direction of sinus aortae) and the distal side thereof. In addition, there is a so-called "in situ arterial grafting" whereby an appropriate arterial blood vessel such as an internal thoracic artery is led for anastomosis to the distal side of the coronary artery, which has fallen short of oxygen due to deteriorated blood circulation, thereby, supplying arterial blood to the distal side thereof. However, the former grafting method whereby a special circumventive blood vessel is formed between the proximal side and the distal side as mentioned above is not good at grafting patency in the long run because venous valves subsist in the venous blood vessel excised from the lower limb. Under the circumstances, there is a recent tendency for the cardiovascular surgery practitioners to rather use the latter grafting method than the former. In turn, even in the latter grafting method utilizing an arterial blood vessel, there are some cases where a so-called "free arterial grafting" is performed whereby an arterial blood vessel is excised in the same way as the former so as to form a circumventive vessel between the proximal side of the artery (in the direction of sinus aortae) and the distal side thereof. In this case, it is an arterial blood vessel that is used as a grafting material, but it is much inferior to the latter grafting method because the vessel cells become extinct after the vessel has been excised, though it could be better than the former. For this reason, except for insignificant coronary artery related diseases, the latter method is normally adopted for such coronary artery diseases as being likely to risk the patients' lives.
Not to change the subject, even with such latest grafting method as "in situ arterial grafting" as mentioned above, the coronary artery bypass surgery is performed by using a lung-heart machine with the patients' heartbeat halted. This is because it is prerequisite to temporarily halt the heart for accurate dissection and anastomosis in view of the fact that arterial blood is incessantly pressurized to flow into the coronary artery in addition to the fact that said artery has so small diameter of 1 mm to 2.5 mm that careful surgical operation must be performed.
However, it surely brings about big worry for the patient to halt his/her heart even though he/she knows that it temporarily stops. This causes the patient to hesitate accepting the coronary artery bypass surgery. Seldom heard, but there have been reported a few cases where the heart halted for the coronary artery bypass surgery by means of the state-of-the-art lung-heart machine did not recover after the operation so that the surgery must be sometimes very risky. Moreover, it is a well-known fact that this surgery often causes complications to the patients and badly affects them not only during operation, but also after it when they recover themselves from the operation. For your reference, it is a medical practice in Japan that after the patients having been placed under the strict supervision of the medical staff in an intensive care unit for three to seven days after the surgery, they are shifted to a general nursing room where they stay for about one month. Thereafter, they are obliged to stay at home for at least three months till they reinstate themselves at work.
Under the circumstances, the coronary artery bypass surgery by means of minimally invasive thoracotomy undertaken on the beating heart that is professionally called a minimal invasive coronary artery bypass surgery has been proposed in the Western hemisphere since around 1994. The number of the Japanese cardiovascular practitioners who tries to undertake this surgery has gradually increased since then so that the Japanese patients are also now open to this surgery to do without a lung-heart machine. The convenience with such coronary artery surgery as mentioned above where it is undertaken on the patient's beating heart or free from a lung-heart machine is practically shown in the fact reported by a Western academy of medicine advanced in the cardiovascular surgery that an anonymous patient recovered himself from the operation quickly enough to leave hospital for a few days after the operation and reinstate himself at work after one week therefrom. In this regard, since this surgery does not require either a lung-heart machine into which such an expensive integrated circuit of disposable type is incorporated as amounting to about 300,000 yens in Japanese currency unit as of 1997 or an artificial lung amounting to about 200,000 to 300,000 yens in Japanese currency unit as of 1997, it results that the medical expenses are greatly reduced in the patients' favor.
However, for such coronary artery bypass surgery as mentioned above, because the coronary artery having a very small diameter must be dissected and then such an appropriate arterial blood vessel as an internal thoracic artery must be led for anastomosis thereto, it requires an extremely high-advanced surgical skill to quickly, but securely anastomose those two arterial blood vessels on the surface of the heart which continuously beats and which it is very hard to visually observe due to the bleeding. That is to say, according to the recent coronary artery bypass surgery undertaken on the patient's beating heart, the coronary artery is temporarily occluded by performing a looping ligation on both the proximal and distal sides of the artery to be performed anastomosis with such monofilament made of low poisonous synthetic resin such as polypropylene and polyethylene or such venom-free synthetic rubber filament as made of silicone rubber, thereby, anastomosis is performed while the blood flow is suspended. In this case, since it is required to stably fix an arterial portion to be performed anastomosis, the ligature is pulled up so as to fix said portion in suspension. However, In reality, this fixation was hard to succeed not only because it is very likely to cause myocardial tear, injury of the coronary artery branches and such complication as embolism of focal arteriosclerosis in the coronary artery when the circumference of the artery is squeezed with said ligature, but also because a locally suspended portion of the coronary artery is subjected to damage and tear as well as distant coronary stenosis.
In order to solve such inconveniences as encountered with said ligation, a so-called "local myocardial compression device" wherein myocardial portions on both sides of the coronary artery on which anastomosis is performed are compressed with two forked members respectively so as to fix an arterial portion to be anastomosed has been proposed.
It is indeed that the considerably stable fixation of a portion of the coronary artery to be anastomosed can be achieved with this prior device. However, this device is intended to fix a portion to be anastomosed by locally compressing the heart so hard that the considerable deterioration of cardiac function is locally observed particularly in the case of coronary artery bypass surgery undertaken on the patient's beating heart where a lung-heart machine is not supplementarily used for blood circulation, and such issue in the prior arts as bleeding from a locally dissected coronary artery for anastomosis is still pending with the result that such complications on the coronary artery as encountered with said ligation remain unsolved.